The present invention is generally directed to an inserting apparatus and method, such as the type of apparatus and method useful in performing mail inserting operations in which an insert is inserted into an envelope for subsequent processing. More particularly, the present invention is directed to an inserting apparatus and method capable of adaptively controlling one or more actuated components in response to a change in the cycle speed of the apparatus.
Mail insertion machines implementing continuous motion, or at least substantially continuous motion, have been developed in the past. A basic function of such machines is to establish a flow of inserts, such as documents or other sheet-type products, establish a flow of envelopes, and combine both flows into a single, common feed path. Once a given insert and a given envelope enter the common feed path, the insert must be inserted into the opened envelope at a common insertion point, after which point the stuffed envelope is transported downstream along a single output path for subsequent processing. In the continuous motion-type insertion machine, an effort is made to increase throughput by reducing the number of times the feed path must be stopped and/or reducing the duration of the stoppage. This has been accomplished by transporting the inserts along the feed path at a higher speed than the envelopes, or by at least accelerating the inserts in relation to the envelopes, so that a given insert xe2x80x9covertakesxe2x80x9d or catches up to its corresponding, aligned envelope and is completely inserted into the envelope with minimal stoppage of the flow of either the insert or the envelope along the feed path.
As will be appreciated by persons skilled in the art, the successful operation of the above-described mail insertion machine depends upon adequate synchronization of the various moving components involved in carrying out the insertion process. It is often desirable to change the overall speed of the machine, such as when differently-sized inserts and/or envelopes are to be processed, in which case steps must be taken to ensure all moving components are still synchronized at the different machine speed. For example, in U.S. Pat. No. 3,423,900 to Orsinger, a continuous motion inserting machine is disclosed in which all moving components, such as the envelope feeding and insert feeding mechanisms, are entirely mechanically linked together. It can be appreciated that any change in the operating speed of such a machine would necessitate laborious mechanical adjustments of several components in order to preserve synchronization.
Even with the modern development of servo motors and motion controllers, satisfactory methods have not heretofore been developed for interfacing such modern control components with mail inserting machines for the purpose of maintaining synchronization in response to varied machine speeds, particularly in the context of continuous motion-type inserting machines. Indeed, the use of modern machine components often exacerbates the problem of synchronization. This has been particularly observed in the case of modern, variable-speed, cyclical mail inserting machines. During the operation of such machines, the duration of time between certain events vary according to overall machine speed. These machines, however, contain both servo motor-driven components or assemblies and actuator-driven components. The respective operating speeds of the motor-driven components or assemblies can be easily controlled and varied by a motion controller. At the same time, however, the respective activation speeds of the actuator-driven components (i.e., the duration of time required for the component to move from its inactive or OFF state to its active or ON state) are inherently fixed and thus cannot be forced to vary. It can therefore be appreciated that the use of variable-speed components together with fixed-speed components renders synchronization difficult.
As an example, a variable-speed cyclical machine contains one or more rotating assemblies or components whose respective operating speeds somehow depend on the master speed of the machine (such as through actual linkage to the main drive shaft of the machine, or simply due to the requisite timing relation among the various moving components of the machine). If, for example, the machine is running at a machine speed of 1 cycle per second, the machine takes 250 milliseconds to move through 90 degrees of its machine cycle. If the speed of the machine is increased to 5 cycles per second, the machine now takes only 50 milliseconds to move through the same 90 degrees of the machine cycle at this new machine speed. As part of its operation, the machine can further contain at least one component driven by a solenoid. As a general matter, solenoids take a constant duration of time to become active (e.g., the time required for the plunger of the solenoid to fully extend outwardly and actually cause the required actuation event), and this activation time is completely independent of the machine speed. In the present example, the solenoid takes 50 milliseconds to become active. The successful operation of this machine dictates that the solenoid be fully active at a given point in time during the machine cycle (e.g., 90 degrees). In addition, the operation requires that the solenoid be inactive until another given point during the cycle (e.g., 85 degrees). Accordingly, there exists no common point during any machine cycle at which the solenoid can be turned ON for all speeds over which the machine is intended to operate.
Continuing with the present example, at the machine rate of one cycle per second, the machine travels 18 degrees (90 degrees divided by 5) in 50 milliseconds (250 milliseconds divided by 5). At this rate, the solenoid must be activated, or fired, at 72 degrees (90 degrees minus 18 degrees) in order for the solenoid to be fully activated at 90 degrees. This is because, upon the initial energizing of this particular solenoid, it always takes 50 milliseconds for the solenoid to become completely active. In the present example, at 1 cycle per second, 50 milliseconds corresponds to 18 degrees of rotation through the machine cycle. As discussed above, at the machine rate of 5 cycles per second, the machine travels 90 degrees in 50 milliseconds. Hence, at this increased machine cycle speed, the solenoid must fire at 0 degrees in order to be fully activated at 90 degrees (because at 5 cycles per second, 50 milliseconds corresponds to 90 degrees, instead of 18 degrees in the case of a cycle speed of 1 cycle per second).
It can thus be seen that if the machine has been operating at 5 cycles per second and the solenoid is correctly set to fire at 0 degrees at that machine speed, the solenoid will fire at the wrong time if the machine speed is changed. In the specific example, if the machine speed is decreased to 1 cycle per second and the solenoid fires at 0 degrees, the solenoid will become fully active at 18 degrees, which is much too early during the machine cycle if the machine is running at 1 cycle per second. One the other hand, if the solenoid is set to fire correctly (at 72 degrees) while the machine speed is 1 cycle per second, and the machine is actually running at 5 cycles per second, then the solenoid will not be fired until the machine cycle reaches 72 degrees and thus will not be active until 162 degrees (72 degrees plus 90 degrees, where 90 degrees corresponds to the fixed activation time of the solenoid, 50 milliseconds, at the machine speed of 5 cycles per second), which is much too late.
In either scenario, the solenoid will fire, and thus eventually become fully active, at the wrong point in time during the operating cycle of the machine. In the context of a continuous motion inserting machine, as well as in other types of machines requiring coordination and synchronization of different moving components, the improper activation time of the solenoid could result in an insert or an envelope failing to be presented at the proper time into the feed path, an envelope failing to open, an insert failing to be completely inserted into an envelope prior to ejection to downstream processes, and so on.
One approach to maintaining proper control and synchronization in a variable-speed inserter machine is disclosed in the following series of related disclosures: U.S. Pat. Nos. 5,823,521; 5,941,516; 5,949,687; 5,954,323; and 5,975,514; all of which issued to Emigh et al. and are owned by Bell and Howell Mail and Messaging Technologies Co. In the main embodiment disclosed in these patents, a Phillipsburg-type mail inserter machine has twelve stations or subassemblies, all of which operate (i.e., are activated and deactivated) in timed relation over the 360-degree timing cycle of the inserter machine. The respective operations of these stations is put under computer-driven, adaptive control, in order to compensate for the electromechanical time lags exhibited by certain components such as pneumatic cylinders that require extension and retraction. As a result, the ON-OFF control signal used to initiate and terminate the respective electromechanical functions of the actuator-type components can be adjusted in response to a change in machine speed, thereby maintaining correct timing of the various components.
In the Emigh et al. patents, the adaptive control is implemented by programming xe2x80x9clook-upxe2x80x9d speed tables into the control software executed by the computer. These speed tables include the correct start angles (i.e., the timing for an ON control signal) and stop angles (i.e., the timing for an OFF control signal) for each station requiring such control. A xe2x80x9clowxe2x80x9d speed table, derived empirically, is provided for the machine operating within the range of 0-2000 cycles per hour. Additionally, the respective time lags (or activation times) for the various actuator-type components are empirically measured, and the resulting value stored in an xe2x80x9coperational delayxe2x80x9d look-up table. The values from the operational delay tables are used together with the cycle speed of the machine to calculate adaptive adjustment factors, which in turn are used in further calculations to determine new start and stop angles for a different cycle speed. These new values are entered into a new speed table. This process is carried out until five successive speed tables are generated, each corresponding to a cycle speed range of 2,000 cycles per hour in width, such that the five speed tables cover the operation of the machine over a total range of 0-10,000 cycles per hour. The mail inserter machine is ready for operation only after all five predetermined speed tables have been stored in memory.
During operation of the mail inserter machine disclosed in the Emigh et al. patents, the computer samples the output of a tachometer such as an absolute optical encoder interfaced with the main drive shaft of the machine. This sampling is rigidly performed at constant intervals as dictated by a clock speed, regardless of what the machine is actually doing. In the specific embodiment disclosed, the sampling is taken without exception every 100 milliseconds. Based on the cycle speed measured by the encoder, the computer selects the appropriate speed table and uses the values from the selected speed table to determine the proper control signals to be issued to the actuator-type components. As an alternative, the computer can use the low speed table and the operational delay table to update a new speed table every 100 milliseconds. It is disclosed, however, that this latter method has the disadvantage of possibly slowing down the computer due to the CPU having to make repetitive calculations every 100 milliseconds.
It would be therefore be advantageous to provide a method and apparatus for more precisely controlling and adjusting actuators in response to variable machine speeds on a substantially continuous basis, particularly in the operating environment of continuous motion inserting machines, in order to more easily and precisely maintain synchronization after a speed adjustment occurs, and further to ensure more consistent performance during ramp-up and shutdown portions of the machine cycle.
The present invention provides a method for controlling a machine that operates over a master cycle at variable cycle speeds, and that includes one or more assemblies which perform rotational movements in synchrony and in combination with one or more other actuated peripheral devices. The peripheral devices are activated by actuators such as solenoids known to exhibit generally constant time lags. Conventionally, such machines are not capable of operating at different cycle speeds, since such a change has in the past thrown the rotational assemblies out of synchronization with the peripheral devices. The method according to the present invention, however, has the advantageous feature of being able to make on-the-fly adjustments to solenoid timing in response to changing cycle speed, and thus efficiently maintain synchronization. This method is implemented by a motion controller or other suitable device capable of electronic processing of an instruction set for performing position-based velocity compensation. The method has been successfully demonstrated in the environment of a continuous motion inserting apparatus, such as the type employed in mail processing jobs, although it will be understood that the present invention will have application outside the immediate scope of the continuous motion inserting apparatus. The present invention can be implemented in mail inserting machines other than the continuous-motion type, as well as any machine requiring synchronization among rotational and actuated components.
According to one embodiment of the present invention, an inserting apparatus operable over a range of master cycle speeds comprises a master drive assembly, an encoder, an insert conveyor assembly, an envelope conveyor assembly, a first actuator, and a motion controller. The master drive assembly is operative over a master cycle and at variable master cycle speeds. The encoder is operatively coupled to the master drive assembly, and is adapted to produce an encoder signal indicative of a current master cycle speed at which the master drive assembly is operating. The insert conveyor assembly is driven by a first motor at a variable insert conveyor speed. The envelope conveyor assembly is driven by a second motor at a variable envelope conveyor speed. During any master cycle, the insert conveyor assembly speed can be greater than the envelope conveyor assembly speed in order to implement continuous-motion inserting operations. The first actuator has a substantially constant activation time lag, and is disposed in actuating communication with a first peripheral device. The motion controller controls the insert conveyor assembly speed, the envelope conveyor assembly speed and an activation position of the first actuator based on the encoder signal. Accordingly, the motion controller electrically communicates with the encoder, the first motor, the second motor and the first actuator. Once during every master cycle, the motion controller calculates the first actuator activation position, and causes the first actuator to be activated at the calculated first actuator activation position.
According to another embodiment of the present invention, the inserting apparatus includes a computer program product comprising computer-executable instructions embodied in a computer-readable medium. The computer program product communicates with the motion controller and is adapted to, once during every master cycle, calculate the first actuator activation position and cause the first actuator to be activated at the calculated first actuator activation position.
According to yet another embodiment of the present invention, a method is provided for controlling an inserting apparatus over a range of master cycle speeds. The method encompasses monitoring a master cycle speed at which an inserting apparatus operates over a plurality of master cycles, and determining when a new master cycle has begun. Once during every master cycle of operation of the inserting apparatus, a first calculation is performed. The first calculation determines a first cyclical position of the new master cycle at which an actuated device should begin to be activated. The calculation is based on the master cycle speed measured for the new master cycle, a predetermined time duration required for the actuated device to become fully active, and a predetermined cyclical position of the new master cycle at which the actuated device should be fully active. The actuated device is caused to begin to be activated when the new master cycle reaches or exceeds the calculated first cyclical position.
According to still another embodiment of the present invention, the method also encompasses, once during every master cycle of operation of the inserting apparatus, performing a second calculation to determine a second cyclical position of the new master cycle at which an actuated device should begin to be deactivated. This calculation is based on the master cycle speed measured for the new master cycle, a predetermined time duration required for the actuated device to become inactive, and a predetermined cyclical position of the new master cycle at which the actuated device should be fully inactive. The actuated device is caused to become inactive when the new master cycle reaches or exceeds the calculated second cyclical position.
According to a further embodiment of the present invention, the method is implemented by a computer program product comprising computer-executable instructions embodied in a computer-readable medium.
According to a still further embodiment of the present invention, a method is provided for continuously inserting inserts into corresponding envelopes in a controlled manner, and over a range of master cycle speeds at which an inserting apparatus operates. The method encompasses monitoring a master cycle speed at which an inserting apparatus operates over a plurality of master cycles, and determining when a new master cycle has begun. Once during every master cycle of operation of the inserting apparatus, a first calculation is performed. The first calculation determines a first cyclical position of the new master cycle at which an actuated device should begin to be activated. The calculation is based on the master cycle speed measured for the new master cycle, a predetermined time duration required for the actuated device to become fully active, and a predetermined cyclical position of the new master cycle at which the actuated device should be fully active. The actuated device is caused to begin to be activated when the new master cycle reaches or exceeds the calculated first cyclical position. Activation of the actuated device assists in an inserting process performed by the inserting apparatus, such as by opening an envelope prior to insertion, registering an envelope, or transporting the stuffed envelope away at the correct point in time during the machine cycle.
The method further encompasses feeding an insert along a feed path at an insert feed rate in timed relation with the activation of the actuated device, and likewise feeding an envelope along the feed path at an envelope feed rate in timed relation with the activation of the actuated device. The insert feed rate is greater than the envelope feed rate, so that the insert is caused to be inserted into the envelope, again in timed relation with the activation of the actuated device.
It is therefore an object of the present invention to provide an improved continuous motion inserting machine and an improved inserting method, wherein tight control and synchronization of the various moving components can be maintained over a wide range of machine speeds.
It is another object of the present invention to provide an inserting machine and related method that include a motion controller or other electronic processing device, which motion controller is capable of calculating in real time the correct cyclic positioning of certain actuated components during operation of the inserting machine, so that a change in machine speed will not require a reconfiguration of one of more machine components.
It is yet another object of the present invention to provide an inserting machine and related method that update the activation times of certain components every master rotation or master cycle of the inserting machine, such that the frequency of the updating process varies directly with the speed of the master cycle.
Some of the objects of the invention having been stated hereinabove, other objects will become evident as the description proceeds when taken in connection with the accompanying drawings as best described hereinbelow.